URTI's Flashcards
What is the most significant method for transmission of the common cold?
Hands (droplet is less significant)
Describe the infectivity of the common cold
Viral shedding peaks on 3rd day, coinciding with peak symptoms. Low level shedding continues for 2 weeks.
What is the incubation period of the common cold?
24-72 hours
Name some viruses that cause the common cold
Rhinovirus, RSV, influenza, parainfluenza, adenovirus, enterovirus, coronavirus, human metapneumovirus
Briefly outline the pathogenesis of the common cold
- Virus deposited on nasal/conjunctival mucosa - attaches via host cell receptors
- Viral replication - host defence activated as cells are damaged
- Cytokine release (IL-8) attracts PMNs
- Increase in nasal secretions and slowed mucociliary clearance
Severity of symptoms of the common cold correlate with what?
IL-8 level
Rhinovirus infection results in the release of albumin and bradykinins, what is the outcome of this?
- Increased vascular permeability in nasal lamina propria
2. Bradykinins cause rhinitis, sore throat
What are the symptoms of the common cold in an infant?
Fever and and nasal discharge
What is the duration of the common cold?
10 days. Prolonged in smokers. Can last 2-3 weeks
What should be on your differential Dx (DDx) if you suspect the common cold?
- Allergic rhinitis
- Acute bacterial sinusitis
- Nasal foreign body
- Pertussis
- Structural abnormalities of the nose/sinuses
- Influenza
- Bacterial pharyngitis
What are some OTC recommendations for the common cold?
- Antipyretic/pain control
- Saline irrigation
- Steam inhalation
- Decongestants
The majority of the cases of pharyngitis are due to what?
Viruses
20-30% of sore throats in children and 5-15% in adults are attributed to this…
GAS (S. pyogenes)
Pharyngitis is unusual in children under the age of 3, T of F?
True, it is most common in school aged children.
What is the incubation period for GAS pharyngitis?
2-5 days
What is the infectivity of GAS pharyngitis?
- Highly communicable
2. Usually non-infectious within 24 hrs of antibiotic therapy
How is GAS pharyngitis spread?
- Person to person
2. Respiratory droplet
Viral pharyngitis is caused only by respiratory viruses, T or F?
False. Non-respiratory viruses may also be responsible.
Describe some of the virulence factors that S. pyogenes has.
- Capsule - hyaluronic acid (camouflage)
- M proteins - resist phagocytosis
- Invasins and exotoxins (hemolysins) - cause tissue damage
- Streptolysin O - cytotoxin (including myocardium)
If GAS pharyngitis is left untreated or is treated inappropriately, what risk does this pose?
3% risk of Rheumatic fever
What collection of clinical features may indicate a viral etiology for pharyngitis? (6)
- Conjunctivitis
- Cough
- Hoarseness
- Rhinorrhea
- Diarrhea
- Rash
What are the typical S/S of GAS pharyngitis? (4)
- Pharyngeal or tonsillar exudate
- Fever
- Tender/enlarged anterior cervical lymph nodes
- Absence of cough
When should you not test someone who presents with pharyngitis?
If the the S/S suggest a viral cause
What testing is available if you suspect bacterial pharyngitis?
- Throat culture
2. Rapid antigen detection test (RADT)
How should you manage viral pharyngitis?
- Symptomatic therapy: analgesic/antipyretic
2. NO ANTIBIOTICS
What is the Tx for GAS pharyngitis?
- Penicillin x 10 days
2. OR Clindamycin
List some benefits of antibiotic Tx for GAS pharyngitis
- Prevents complications (i.e. peritonsillar abscess, cervical lymphadenitis, rheumatic fever)
- Decreases transmission
- MINIMAL symptom improvement
In what age group is acute otitis media most prevalent?
Infants
List some risks factors for acute otitis media
Age (6-18 months), family Hx, daycare, lack of breastfeeding, tobacco smoke or air pollution, pacifier use, First Nations, poverty, lack of access to care
What is the etiology of acute otitis media in 2/3 of patients?
Viral and bacterial combination
What 2 factors are essential in the patho. of AOM?
- Antecedent viral URTI
2. Colonization with a respiratory bacterial infection
Briefly describe the patho. of AOM
- Inflammation in response to virus obstructs isthmus of Eustachian tube
- Obstruction causes -ve pressure leading to the build up of secretions
- Bacteria colonizing the URT enter the middle ear and growth in the secretions
S/S’s of AOM in children can include: (4)
- Otalgia
- Bulging of the tympanic membrane
- Otorrhea
- Hearing loss
List 5 complications of AOM
- Vertigo
- Tinnitus
- Facial paralysis
- Mastoiditis
- Meningitis
What is included in the Tx of AOM
- Watchful waiting
- Pain relief
- Amoxicillin (best coverage for S. pneumoniae)
Why is a 3 month follow up recommended for AOM?
To assess for the presence of fluid in the ear, which can lead to hearing loss if not corrected.
What is the spontaneous resolution rate of acute sinusitis?
About 70%
What the most common cause of acute sinusitis?
Viral is 200X more common than bacterial
3 viral agents that can cause acute sinusitis
- Rhinovirus
- Influenza
- Parainfluenza
What is the natural progression of acute viral sinusitis?
Typically resolves in 7-10 days
List some bacteria that may cause acute sinusitis
- S. pneumoniae
- H. influenzae
- M. catarrhalis
- Anaerobes (associated with dental disease)
Briefly outline the patho. of acute sinusitis
- Common cold –> viral rhinitis –> spreads to paranasal sinuses
- Inflammation of sinuses = impairment of mucociliary defences, and 2ndary spread of bacteria into nasal cavities
What conditions predispose someone to acute sinusitis (4)
- Dental infections
- Allergies
- Swimming
- Mechanical obstruction of nose
What imaging is recommended for acute sinusitis: A - X-ray B - CT C - MRI D - None of the above
D - imaging is not recommended
How do you Dx acute sinusitis?
- Based on Hx and physical exam (purulent rhinorrhea, nasal congestion)
To Dx bacterial sinusitis…
- URTI symptoms for > 10 days or worse after 5-7
AND, nasal congestion/purulent nasal discharge + facial pain - with or w/o fever/maxillary tooth ache/facial swelling
How do you manage acute sinusitis?
- Analgesics
- Steam inhalation
- Decongestants
- NO ANTIHISTAMINES
- Selective antibiotic therapy = amoxicillin
Croup is AKA…
Laryngotracheitis
What is Croup?
Self-limited illness characterized by inflammation of larynx and trachea
Croup is most common for what age group?
- 6-36 months
2. Rare beyond 6 yrs of age
What time of day is Croup most common?
- Late evening or early morning
2. Recurrences are common
What is the most common cause of Croup?
Parainfluenza virus type 1
Briefly describe the patho. of Croup?
- Virus infects nasal pharyngeal mucosa
- It invades respiratory epithelium and causes inflammation of cartilage in subglottic region
- This narrows the trachea
- Fibrinous exudates may worsen narrowing
What may predispose someone to Croup? (3)
- Genetics (differing immune response to Parainfluenza virus)
- Anatomic narrowing
- Hyperactive airways
What is the typical presentation of Croup?
- Sudden onset (inspiratory stridor, cough, hoarseness)
- Rapidly progressive
- Previous Hx of Croup
What is the hallmark of Croup in infants?
Barking cough
What is the DDx for Croup?
- Epiglottitis (throat pn more prominent, difficulty swallowing, LOTS OF SALIVA, high fever)
- Pharyngitis
- Foreign body aspiration
- Allergic reaction (swelling of lips/tongue, rash)
- Peritonsillar abscess (enlarged lymph nodes, tonsillar asymmetry
Outline the management of Croup
- NO ANTIBIOTICS (viral)
- Systemic/nebulized steroids
If severe:
- Nebulized epi
- Blow-by O2 if hypoxic
- NO SEDATION
Whooping cough is: A - a boy band B - not a big deal C - highly contagious RT infection D - none of the above
C
Pertussis occurs in cyclic epidemics every: A - 3 years B - year C - decade D - 2-5 years
D
How is Pertussis transmitted?
- Direct contact
2. Inhalation of respiratory droplets
What is the incubation period of Pertussis?
7-10 days (4-21 days)
What causes Whooping Cough?
Bordetella pertussis
Features of B. pertussis (3)
- Obligate human pathogen
- Fastidious Gram -ve coccobacilli
- Needs special growth medium
List some virulence factors of B. pertussis
- Adhesins
- Tracheal cytotoxin/dermonecrotic toxin
- Interferes with host immune system
- Endotoxins
Classic clinical manifestations of Pertussis (3)
- Paroxysmal cough
- Inspiratory whoop
- Post-tussive emesis
In which age group is Pertussis most deadly?
Infants
What labs can be performed if you suspect Pertussis?
- cough < 3 weeks = nasopharyngeal swab for culture and PCR
2. cough > 3 weeks = PCR
What is the antibiotic therapy for Pertussis?
- Macrolide or TMP-SMX
What are the potential benefits of antibiotic therapy for Pertussis?
- May reduce duration and severity of cough
2. Limits transmission
When would you give prolonged antibiotic therapy for Pertussis?
- If there is potential for exposure to high risk pt’s (i.e. infants, pregnant women, healthcare worker, childcare worker)
What were the 6 URTI’s presented in lecture?
- Common Cold
- Pharyngitis
- Otitis media
- Sinusitis
- Croup
- Pertussis